Traditional electronic water meters using optical encoder technology for digital counting and measurement have been widely used in the water distribution industry, but the technology has inherent flaws, such as difficult assembly, high failure rate, and poor immunity to interference. With the development of magnetic sensor technology, water meters using magnetic sensing technology for the counting mechanism are gradually beginning to replace optical encoder technology. This is because magnetic sensor technology enables high resolution, good stability, and good interference immunity. For these purposes magnetic angle sensing technology is the best. The operating principle of magneto resistive sensors such as a magnetic angle sensor is that they measure the rotation angle of the magnetic field vector produced by a magnet installed on a numbered wheel, and through a corresponding digital processing unit output a digital value.
Magnetic angle sensor technology has high accuracy and good interference immunity, but because it relies on the intensity of the magnetic field, and it tests the total magnetic field strength, the highest precision results may not be obtained, because sensor and permanent magnet relative placement within the water meter greatly influences accuracy, and additionally a strong field if present will influence the measurement, so measurement accuracy may be greatly reduced if not well implemented. Adopting magnetic angle sensor technology in electronic water meters will require the use of a multiplicity of permanent magnets and sensors, the interference of which will affect electronic water meter accuracy. Additionally, the external magnetic field can affect accuracy.